Electrical transmission of messages



Aug. 9, 1932. B. E. ELDRED ELECTRICAL TRANSMISSION OF MESSAGES FiledSept. 28, 1929 3 Sheets-Sheet 1 NVENTOR /Byra/1 E. E/dred BY fir TTORNEYAug 9, 1932. B. E. ELDRED ELECTRICAL TRANSMISSION OF MESSAGES FiledSept. 28, 1929 3 Sheets-Sheet 2 "2522? Eldrea Aug, 9, 1932. B. E. ELDREDELECTRICAL TRANSMISSION OF MESSAGES Filed Sept. 28, 1929 3 Sheets-Sheet3 HIIIIIIIII:

ELEcTRIc TVHEWIPIII'R Tram gm A RNEYI Patented Aug. 9, 1932 PATET-enact:

mmon a, 21.1mm), or new i631. H. Y.'

v ummcanmmsmssron or uzssaens Application fled September 2 8, 1929.Serial No. 385,822.

marks and symbols of the usual keyboard This invention relates to thetransmission of messages by wire, radio or other electrical means ofcommunication.

One object of the invention is to produce a message in typewritten formsuch that it can be readily read and yet will have different lightcontrolling power, such as translucency or reflection property, for eachdissimilar character of the message and the same light controlling powerf, or each similar character. Another object is to convert the typedmessage, thus arranged, into electrical 1mpulscs for transmission toanother point. Another object of the invention is to produce lightflashes from the electrical impulses previously referred toand thenrecord said light flashes on ai'relatively moving light sensitive filmor other medium, or light sensitive reflecting surface if the reflectingproperties instead of the translucent propertiesare to be used. I

Another object is to produce electrical impulses at a transmittingstation by controlling light by means of the record made from the lightsensitive film or reflecting strip and directing this light onto aphotoelectric cell or similar means to create electrical impulsesproportional to the flashes of light produced by such control and thento transmit such electrical impulses to another point.

Another object of the invention is to receive electrical impulses withintensities proportional to the light controlling power of eachindividual letter, punctuation or spacing character of the originalrecorded message and then to cause each impulse to impress itscorresponding character on a sheet or equivalent recording means. c

Another object is to convert the received impulses into electrical lightflashes proportional in intensity to the intensity of said impulses andthen record said flashes on a light sensitive medium.

Another object is to convert the lastjmenti'oned photographic recordinto electrical impulses proportional to the intensity of the lightflashes and then' causing said impulses to record the letters, figures,punctuation corresponding to such intensity.

Other objects will appear in thefollowing specification, reference.being had to the drawings in which:,

Fig. 1 is a diagrammatic illustration of the method of carrying out therecording of the message in accordance with the invention. Fig. 2 is anillustration of the transmitting part of the invention.

Figure 3 illustrates the receiving part of the transmitted message.

Fig. 4 is a diagrammatic illustration of a section of a film record ofmy invention.

Fig. 5 is a viewv of part of the alphabet showin v the characters withdifierent degrees o shading.

Fi 6 is a view of part of the alphabet with varia le cross hatchin onthe characters.

Fig. 7 is a modifie the letter after the message has been transmitted bymeans of the characters of Fi .6.

Fig. 8 is a further modified form w ere photoelectric cells aresubstituted for the mechanical contact arrangement of Fig. 3.

Fig. 9 is a diagrammatic illustration of a portion of the film at thereceiving end when letters with diflerent cross hatching as in Fig. 6are used at the transmitting end.

It is the resent practice in transmitting messages eit er by radio or bywire to send the message either by means of Morse code, by facsimilemethods or by actually operating typewriter keys at the receiving pointby electrical currents created directly by the hi'mself, cannot read themessage thus prepared to determine whether or not a mistake has beenmade; Also in the'Morse code system a series of electrical impulses mustbe form for reprinting.

'tions; the usual 0 cc help,- and the sender transmitted for eachcharacter of the message which increases the time of transmission. Themessage alsocan be read by both the transmitting OlllCC and thereceiving office and is not, strictly speaking, confidential.

In facsimile transmission electrical impulses are created by light beamscaused to scan or analyze a'mcssage typed on a sheet until the entiresheet has been scanned. This requires a great deal of time, relativelyspeaking, and the electrical impulses sent out to the distant receivingpoint are of great number, which greatly slows down the transmission andreception of the message.

In the operation of electric typewriters at a distance such as used instocktickers, and other similar devices, the speed of transmission isslow because it is limited to speed of operation of the typewriterdirectly connected to the transmission link. The transmission linkcannot be used to full efficiency when coupled directly to slow movingapparatus. Also messages received in this way are not strictlyconfidential as the person receiving the message, of course, can readit.

There are various other objections to the existing methods oftransmitting and receiving messages and other communications and certainof these will be apparent by referring to the advantages of my inventionover known systems.

In accordance with my invention I arrange the type on a typewriter,printing machine or similar device so that the impression or record madeby the letters of the alphabet, numerals, symbols, punctuation marks andspaces will have different light controlling properties either inrespect to translucency or in respect to reflection.

Speaking entirely by way of example, a square or other shaped space of arecord on which the letter A is impressed would permit a given quantityof light Z to pass therethrough or be reflected therefrom, as the casemay be. The letter 13 could be arranged to pass a quantity of lightequal to (L). The letter C would pass the light k l, the letter D, lc l,etc. It is not absolutely necessary to use numerals, punctuation marksor to distinguish between capitals and small letters, 1n messages, aswill be seen by noting the prac tice in the transmission of present daytelegraph messages. The numerals and punctuation markscould be spelledout and all letters could be capitals, if desired, but by my system Ican arrange all of these so that they would be made with different lightcontrolling powers either by variations in translucency or in reflectionproperties.

The shape of the type causing the typing through carbon ribbons or bymeans of inked surfaces or by other means could be arranged so that theimpressions would produce the variation in translucency or reflectionproperties while still preserving the readable nature of the charactersthus made. In some cases, if desired, the light controlling power of thecharacters might be obtained by using substantially the present shape oftype with bars or frames of black or light impeding surfaces arrangednext to the letter or other character.

WVhen a message is made by a typewriter or other typing or printingmachine as ust de scribed, it may be readily interpreted by thestenographer as it is being typed or otherwise made. When a mistake ismade in the typed message the stenographer can immediately note themistake and correct it in the usual way. Carbon copies of the message tobe transmitted also may be made and can be kept in the files forpermanent record, which copies may be read by any clerk in the ofiicewho can read the language in which it was typed. The message thus typedwith varying degrees of light controlling power for each character ofthe message may be transmitted to and re ceived at other points by themethod which will now'be described in greater detail.

Light from any source-such as lamp 1, is condensed by corrected lens 2on to the typed sheet 8 through a member 4 having an appropriate slittherein with which an appropriate rotating shutter 3 may be used. Inpractice the slit member would be preferably arranged close to the typedsheet, but for purposes of illustration it is shown spaced therefrom.The light coming through the slit would be projected on the area of thepaper or other material receiving the impression of, say, the letter A.The light passing through this space would be impeded by the opaquenesscaused by the letter itself. This character might be entirely opaque oronly relatively so. The light that proceeds through the space allottedto this letter A would impinge on the cathode of a photoelectric cell 7.This would cause in a well known way the passing of electrons from thecathode to the anode. The photoelectric cell would be connected to theusual vacuum tube amplifier 7, a detail description of which is notnecessary for the understanding of this invention. The amplifiedimpulses would pass through a coil 8 controlling a mirror 9 which wouldreflect varying quantities of light from a light source 10 through alens 11 and slot 11 and on to a light sensitive film 12, caused to moveat the proper speed by well known means such as are used in talkingmotion-pictures and other sound recording apparatus. This flash of lightproduced by the movement of the mirror would produce, for example, whenthe film is developed, a pulse such as is shown at A of Fig. 4. This isthe socalled variable area type of record more fully described in mycopending application serial No. 395,820, filed Sept. 28, 1929, soundrecords and method of making the same. The amplifier and the oscillatingmirror may be constructed in any way, for example, along the linesdisclosed in that a plication. The slot is intended to be optica lyreduced, as described in my Patent 1,665,811, January 11, 1928. v Whenthe'letter A has thus been recorded on the film 12 the sheet 3 would bestepped to one side by any typewriter mechanism. The typewritermechanism is not shown as it may be of any well known construction.Arrows have been used instead to indicate thatthe sheet passes back andforth and is fed verticall This brings the next adjacent letter of themessage in front of the slot 4. If this were the letter N of the wordand a predetermined quantity of light would pass through the spaceallotted to the letter N and in the manner already described a recordwould be made on film 12 that would, after development, look torexample, as indicated at N in Fig. 4. The sheet 3 would then he steppedfurther to one sideuntil letter D of Fthe word and for example, passedunder the light spot produced by slot member '4. By the means alreaddescribed a record of this character would be made on film 12 thatmight, for example, appearas at D of Fig. 4 when the film is develo ed.The shape of the variable area reco for letters of the word and has beenassumed by way of ex- 3 ample only. An shape desired may be pre-'determined for t ese letters. The only distinction is that they shouldbe difierent from each other. Also, variable density recordingmay bemade as described in my copending application referred to herein. Whenthe end of the word and has been reached, for example, the area allottedto the space between this word and the next word would pass a certainquantity of light when w this area is passed under the light spot causedby slot member 4. Preferably this area ass1gned to thespacing characterwould have the translucency of the sheet of paper on which the messageis typed or printed, that is,

46 it would have greater light transmitting or controlling power thanthe letter or punctuation characters. This would produce a record suchas 14 in Fig. 4, the top portion being out 01f in this figure as thisFig. 4 gives only a section of the record assumed in this case.

This record in Fig. 4 also may be a positive or negative afterdevelopment and the white and lackspaces are made in this figure merelyto show the type of records that could 55 be made in the methoddisclosed without reference to the positive or negative nature of therecord. Words of the line being recorded would be recorded in exactlythe same way as the word .and and the words occurring to thereafter inthis line would also be recorded in this way. When the end of the lineis reached appropriate and well known mechanism would come into play tomove upwardly suificiently to bring the next line of the message intoposition. Also at this time the sheet 3 would have been moved to bringthe first part of the line under the spot of hght. In this w'ay'theentire pa e of the-message is brought before the spot 0% light insuccession and a recordmadeon the moving film 12. All of these steps inthe method would have taken place rapidly by appropriate mechamsm.

To preserve messa es in secrecy the film record 12 may be ma e inapparatus located and controlled-by the oflice or'person desiring totransmit the message. The film would then be sent to the transmittingcompany for transmission to the desired distant point, as will "now bedescribed. 'The development of the fihn could behandledeither by the customer or the transmitting company or by anyone else.

The transmission system is more or less dia grammatically illustrated inFig. 2. The film'12 of Fig. 1 is placed on appropriate reels of suitableapparatus such as is well known in the motion picture art and is passedrapidly in front of a'source of light 15, The light passes through lens16 and through a slot 17 on to film 12 to throw a spot of lightsuccessively on to the recorded impulses such'as A, N, D and 14, forexample, of Fig. 4. A varying quantity of light will pass through this 4record and onto the cathode of photoelectric cell 18. -An electrical imulse will then pass from photoelectric cel corresponding to the amou oflight passing through the film allotted to record A of Fi 4. Thispreferably would be amplifiekf by vacuum tube amplifier 19 orotheramplifier and assed over the radio or wire link 20, wire eing shownby way of example,

and again amplified at the receiving end if desired by suitableamplifier 21, in the output of'which would be a mirror or other lightcontrolling device 22 by means of suitable coil or magnet 23. Themirrors 9 and 22 may be of any construction, for example, such vas shownin patent to Hoxie, #1,598,377, April 21, 1926. As shown, the mirrorwould control the light coming from light source 24 to producereflecting beams or flashes of light through lens 25 and slot 25 andcondensed on to a light sensitive film 26 moved at appropriate speedpast the condensed light spot by appropriate reels and other mechanism.

As soon as the letter A of. Fig. 4 has been recorded letter N willinstantly ollow thereafter on the film 26, the letter I) immediatelywill be recorded thereafter and then the space 14 will be recorded. Inthis way record 26.

will be a duplicate at the distant end of record. 12.

By the process just described the radio or wire transmission 20 will betied up only a veryshort time, while the record or film 12 is beingrapidly transmitted and the record 26 is being made at the receivingend.. In prior processes where Morse. code, facsimile apparatus, andordinary stock ticker typewriter mechanism is being opera-ted at thetransmitting and receiving end, the transmlssion is slow due to theinherent operationof the relatively slow moving apparatus. W'ith mymethod as just described the apparatus of moving films 12 and 26 isoperated at very high speed and the transmission line or radio link istied up only for a very short time to transmit the message in the mannerdescribed.

By my processa wire line or a radio link is capable of transmittingenormously greater described. The film 26 of Fig. 2 after developmentwill be put on appropriate reels and other apparatus well known in thetalking motion picture and film phonograph art. Light from any source 27will be condensed by lens 28 and slot member 29 on to film 26. The lightpassing through this film will be projected on to the cathode 30 of thephotoelectric cell in well known ways. Continuing the explanation withthe word and, as before, by way of example, the light condensed on thearea allotted to the letter A will have a certain value due to thetranslucency of this area. This quantity of light will produce adefinite current flow into the input circuit of the vacuum tube or otheramplifier 31 by electron flow between the cathode 30 and anode 32, asdescribed more in particular in my above mentioned application. Thiselectric current after amplification will pass into the output circuitcontaining any electromotive arrangement such as any well known deadbeat galvanometer arrangement. I have illustrated in moreor lessdiagrammatic form this galvanometer arrangement in Fig. 3. The outputfrom the amplifier 31 passes through line 33 to hairspring 34 to coil 35and out through a similar hair spring, hidden from View in this figure,and thence back through line 36. This produces electromagnetic forcealong the axis of coil with the north pole in the direction of the arm37 which is attached to and rotates with coil 35. The interactionbetween these magnetic lines of force and those produced by the polepieces whose polarity is indicated by N and S causes the coil and arm 37to rotate clockwise. Let it be supposed that a record for the letter Ais on the film 26 where the light beam is centered. The amount ofcurrent produced by the photoelectric cell will be suificient to swingthe galvanometer arm to'some position, say contact 38. This will causecurrent to flow from battery 39 through strip 40 across contact brushesand connecting strip, generally indicated by 41, to contact strip 38through the connected wire in cable 42 to the electric typewriter 43'.Electric typethe sheet in the electric typewriter and step the sheetforward for the next letter.

As the film 26 moves to the next character N in the word and assumed tobe transmitted, a different quantity of light will pass into thephotoelectric cell and a diiferent value of current will move thearmature arm 37 to some other position on the series of contacts. Merelyby way of example, let it be assumed to move the contact point tocontact 44. This would energize coil 35 and close the contact leading toanother magnet or control member at the keyboard of the typewriter 48.This would cause the electric typewriter to type the letter N on thesheet of paper. The film 26 would then move to the space alloted to theletter D and arm 37 would move the contact in the way described andcause energization of another electromagnet which would cause the letterD to be typed on the sheet of paper in the electric typewriter. lVhenthe area alloted to the space after the latter N comes under the spot oflight passing through the slot member 29 a greater quantity of lightwill be thrown into photocell 30. In the way described this will cause aspacingmagnet on electric typewriter 43 to move the shiftmechanism onthe typewriter to cause a space between letter N already typed on thesheet of paper and the next letter will be typed thereon when 26 movesto the next. letter or character, whatever it may be.

In the way described, the message appearing on film 26 will be typed outon the sheet of paper in the typewriter 43. At the end of the line thetypewriter carriage will automatically reset for another line or aseparate character having a definite light value may be assigned to itfor operation of a control for turning the platen roller and shiftingthe carriage. After the entire message including the typed signature,date, etc. has been typed on this sheet of paper it may be removed anddelivered to the addressee whose name would app-ear at the head of themessage having previously been typed on the original type script orrecord of Fig. 1.

The apparatus diagramn'iatically illustrated in Fig. 3 could be locatedin the oflices of customers, particularly where the amount ofcorrespondence received by this system is sufiiciently large to warrantthe acquiring of such apparatus. In that case the operators in thereceiving oflice of the communication company would be unable to readthe message on film 26. 1 l I Also to render the message confidentialwithout necessitating customers having the 5 transcribing a paratus ofFig. 3, such apparatus when ocated in the receivlng oflice of thecommunication company may be arranged so that the sheet of paper issuingy from typewriter 43 and containing the typed in message isautomatically folded and slid mto an envelo e and sealed by appropriatema; chinery not shown) with the name and I address of the customerappearing through the usual transparent Window of envelopes now on themarket. This could be delivered to the customer 'withoutanyone knowingthe contents. i

In making the original typed script record in holder 3 of Fig. 1 theimpressions could so be made if desired in the form of squares or othershapes having varying degrees oftrans' lucency. Such a type scriptwould, of course, be illegible and would be entirely confidentlal. MWhen transmitted and received by the apparatus of Figs. 2 and 3, asalread described, the message in legible type woul issue from thetypewriter &3. This is not so desirable as the system just describedbecause the typist making the original type script 1n the office of thesender would not be able to read the type script and make correctionsfor errors except by being skilled in the reading of such a code. Forthis reason I prefer have the original type script appearin' ID holder 3ofFig. 1 to appear in readable orm as first described and secrecy can bemaintained especially. in large offices of customers by having theapparatus of Fig. 1 located in f such oflices. The characters themselvesand 40 the squares that are allotted to them may be variously shaded, asillustrated in Flg. 5,

so that each'one will pass or reflect a, difl'er-' ent amount of lightfrom the others. The i typed message could also be maintained confidential by enclosing the sheet of type script, such as would be placedin the holder 3, in a fiat envelope, which could be automatically openedby machinery at the ofiice of the transmitting company and the sheet fedinto the .holder 3 automatically and again sealed when it is recorded onfilm 26. The sealed letter after transmission could then be destroyed,returned to the sender or filed awa in sealed condition for future usein the o ces of the communication company subject only to be opened bappropriate rulesof that company, sucl i as by order of a court.

While I have described by way of example, the use of films for records12 and. 26, it will be understood that tapes having reflecting surfacesuch as' glossy paper, may have a sensitized surface to receive thephotographic record and the light directed into the photoelectric cellsby reflection from the 1 record. This power of directing light into thephotoelectric 0 11s, whether by translucency or reflection property ofthefihns or tapes maybe called for convenience,'the light controllingpower of the characters employed to convey the message.

While I have described the apparatus of Fig. 1 as being associated witha telephone or telegraph wire line, it will be apparent that theapparatus can function in exactly thesame way by associating it witha'radio transmitting and receiving system. It also will be apparent thatthe telephone or telegraph line of Fig. 2- can carry either socalledaudio currents or carry or guide radio frequency currents such as isused intranscontinnetal carrier current systems atthe present time.

I have described the preferred system as embodying all the stepsillustrated in Figs.

1-, 2 and 3 but some of the advantages of my 86 invention can beobtained by making the type script such as is on the sheet in the holder3 of Fig. 1 and sendingthecurrents coming through the amplifier ,8 thatfigure directly into the transmission system of Fi 2. In such asimplified system the electrical typewriter apparatus of Fig. 3 could beconnected directly to the amplifier 21. In this siniplified system films12 and 26 would be eliminated. This'is not the preferred 5 form,however, as the wire line or radio link would be tied up for alonger'time due to the inability of the typing apparatus, associatedwith sheet 3 at the transmitting station and that associated with thegalvanometer in the receiving station, to function as fast as theapparatus that moves films-12 and 26. However, this abbreviated form ofapparatus would have advantages and itis one form of my invention. I Myinvention is therefore directed to the use of all'or any part of thenovel features of the entire system. a

In making the photographic records on films 12 and 26 I may use eitherthespeed films or the slower films of .fine grain emulsion such asreferred to in my copending application Serial No. 395,820 filed Sept.28,

Instead of variable area records I also may use variable density recordswell u known in the art and referred to in that copending application. Ialso may use either the vibrating mirror type of light control, or theneon or other lamp type. both of which are disclosed in no my copendingap 'lication. However, my invention is not llmited to any particulartype of control and the one disclosed in particular herein is suflicientto set forth the principles of thein'vention. Instead of using a typescript depending upon quantity of light'for sending the message, I-mayuse alternatively line impressions on the type script which havedifferent 213,

frequency characteristics, that is, I may make the type so thatimpressions will be caused on the type script having, say L lines forthe letter A. It. for the letter B, k for the letter C, etc. I haveshown a portion of the alphabet in Fig. 6 where the letters havedifferent cross hatching to give the desired frequency of interruptionof the light. The number of cross hatching lines of course areindicative only. 1 may have the cross hatching of the respective lettersdiffer by any amount. These lines could extend across the space allottedto the letters with transluccnt portions in between like the hatching ona drawing. The type script having these impressions made. iip of thedifferent number of lines for each character could then be scanned bybeams of light passing rapidly across the lines of the type script inrapid succession. The light passing through the space allotted to eachcharacter would be interrupted by the hatching and cause a definitefrequency of interruption of the light depending upon the speed ofmovement of the paper, but one frequency would be exactly proportionalto the number of lines on each impression. That is, the lightintcrrupted by the impression for the character A would have a frequencyof say, hf, for the letter B would have a frequency of 71: 7, for theletter a frequency of lc f and so on. The method of scanning, such as infacsimile and television systems is well known in the art and apparatusfor doing this need not be described in detail. The light spot shouldscan one line of light in one sweep across the page instead of in alarge number of sweeps as in facsimile and television work. The light ofdefinite frequency passing through each character when sent into aphotoelectric cell relatively moved with the spot of light would produceelectric impulses of the frequencies corresponding to the frequency ofinterruption of the light by the lines of each character. These electric impulses of definite frequency for each character could be used toproduce a record such as 12 having similar frequency characteristics, orthese impulses if desired could he sent directly over the wire or radiolink. If film record 12 is made with the frequencies as I prefer, themovement of the film in th apparatus of Fig. 2 would produce definitefrequencies to be relayed over the radio or wire link.

In this modification each character would generate a current of a numberof pulses, whereas in the method described in connection with Fig. 1each character generates one pulse only.

Fig. 7 diagrammatically illustrates the electrical system for retypingthe message from the film record made at the receiving end when thecharacters have different frequeney of light interruption as in Fig. 6.The circuits for only a portion of the char- -ruption of the letter A.

acters are used but the others would be similar. In this figure thelight from the lamp 27 would pass through the slotted member 29, lens28, film 26, on to the sensitive electrode 30 of the photoelectric cellthrough the amplifier 45. The output of this amplifier is connected tobus wires 46, 47, and would be impressed between the filament and gridof all of the vacuum tube relays 48, 49, 50, etc. The plate circuitoutput of all these relays feed into their corresponding vacuum tubes51, 52, 53, etc. These are all tuned differently, for example, the gridcircuit of tube 51 would be tuned to the frequency of inter- Thecircuits of 52 and 53 would'be tuned to the frequency of letters I) andC, etc. Since We have assumed that the portion of the. film 26 that atthis instant is receiving the light beam corresponding to the letter A,the tuning of the circuit 51 of this frequency will buildup a very largecurrent in the circuit, whereas the current in the other circuits willnot be built up because the tuning of these circuits is different.Therefore the current will be greatly increased when it passes throughvacuum tube 1. The output of vacuum tube. 51 will be connected to wiresleading to the magnet in the electric typewriter 43 and the letter Awill be typed on the sheet therein. In this way the. movement of thefilament 26 will cause the corresponding letter to be typed in the sheet43. I have illustrated only one tuned vacuum tube stage but I may useany number of such tuned stages in cascade to select and build up thecurrent.

The record made on film 26 at the receiving end by the system of Fig 2when characters of different frequency, as in Fig. 6, are being used,would appear different from the film shown in Fig. 4. I haveschematically illustrated the record on film 26 in this case in Fig. 9.In this figure the letter A would have a certain number of oscillations.the letter B a different number, the letter C a still different number,and so on.

As another alternative method. at the receiving station I may use asensitive dead heat galvanometer with an attached mirror adapted to takea. definite position determined by the intensity of the current receivedover the radio or wire link, as first described. A series ofphotoelectric cells corresponding in number to the number of thecharacters employed in the system would be located in position. toreceive a beam of light as the mirror takes its definite positions inaccordance with the strength of the current received. The retyping ispreferably made from a record like Fig. 4 so as to permit the radio orwire transmission link to be used in continuous operation at high speedfor making the film records at the receiving station. I have showndiagrammatically a system in Fig. 8 for retyping in this way thesuccession and return to sweep across the same message recorded at thereceiving end. In this system similarparts have been given similarreference characters and the galvanometer has been schematically shown.It may be similar in construction to the one shown in Fig. 3 except thatit has a mirror 5 that is rotated by the rotatable coil 35. When theletter A is being retyped from filament 26 light from lamp would bereflected from the mirror 54 to photoelectric cell 56. Cur-f rent fromthis photoelectric cell would be amplified at 57 and the output passedinto wires in the cable 42 to the typewriter 43 where the letter A wouldbe typed in a way already described. The other letters of the alphabetwould be similarly retyped, and the operation need not be furtherdescribed.

' In the system of Fig. 8 the record on the film 26 would be like thatshown in Fig. 4..

The galvanometers in Figs. 3 and 8 would be of dead beat form. It is thepractice at the present time .to make such galvano= meters dead heat byplacing an appropriate resistance 58 across the terminal wires of thecoil 35. Such a resistance prevents the armature from oscillatingbecause an oscillating armature generates currents from the mechanicalmotion. These currents are damped out by the resistance 54 whichtherefore acts as an electrodynamic brake. Consequently the mirror movesquickly to the position corresponding to the strength of the current ofthe character being typed and remains at this osition withoutoscillating. The galvanometer and the damping resistance are old andwell known in the art and have been illustrated digrammatically anddescribed in order to make the operation of the system It is, of course,immaterial, as far as the spirit of the invention is concerned, whetherthe message is typed on a so-called typewriter, or by means of aprinting press or other apparatus.

The type script paper shown in'Fig. 1 may either be arranged with theface of the sheet toward the light source or away therefrom,

that is the type script could be made either to appear as a positive ornegative in respect to the source of light. In either case the mechanismof the apparatus would be arranged so that the letter would be fedrelatively to the spot of light in the proper direction.

My invention broadly distinguishes from facsimile and television systemsin that each letter or other character is scanned or analyzed completelybyv one sweep of the light beams before proceeding to the next character. In the other systems the light beams sweep across the tops'of thecharacters in characters in series for another increment of area. Itthus takes a relatively large number of sweeps of the light to computethe scanning of one line of the typed letter. In

my invention one sweep of the light across the page completely scans oneline, each let-w ter or other character bein completely scanned beforethelight" proce s to the next.

In some cases itmay be desirable to use a rotating shutter as in motionpicture apparatus, to pass the light only while the type characters orspace is stationary.

Paper or sheets of other material of special translucency may be usedfor making the type script record if preferred, but typewriter paper nowon the market will sufljce.

Other modifications may be made without departingfrom the spirit of theinvention.

Having described my invention, what I- claim is:

.1. The method of transmitting a message which consists in making alighteontrolling record of said message, passing light through saidrecord to produce flashes, producing electrical impulses havingintensities proportional to said flashes, and producing impulses atanother point proportional thereto.

2. The method of transmitting a message which consists inmaking a lightcontrolling record of said messa e, passin li ht throu h g g a g saidrecord to produce flashes, producing electrical impulses havingintensities proportional to said flashes, producing at another pointimpulses proportional thereto, and pro- .5

point impulses proportional to the first mentioned impulses, producing arecord of said impulses and converting said. second mentioned recordinto directly readable language.

4. The method of transmitting a message which consists in making arecord of the letter, punctuation, spacing or other characters thereofwith different light controlling power for each dissim lar character andthe same light controlling power for each similar character, producinglight flashes by said characters, producing electrical impulses propor-vtional to the intensity of said flashes, produc ng impulses at anotherpoint proportional to the first mentioned impulses and re-recordingsai dcharacters by means of said impulses.

I 5. The method of transmitting a message which consists 1n making arecord of the latter, punctuation, spacing and other cha-racters thereofwith different light controlling powerfor each dissimilar character andthe same light controlling power foreach similar character, producinglightflashes by said,

characters. producing electrical impulses proportional to the intensityof said flashes, producing at another. point impulses propor- I om CUtional to the first mentioned pulses and rerecording said characters bymeans of said impulses.

(3. The method of communicating messages which consists in typing amessage, completely scanning by light rays each letter character thereofbefore proceeding to the next, producing electrical impulses by saidlight rays and producing at another point electrical impulsesproportional to the first mentioned pulses.

7. The method of communicating messages which consists in typing amessage, completely scanning by light rays each letter character thereofbefore proceeding to the next, producing electrical impulses by saidlight rays, producing at another point electrical impulses proportionalto the first mentioned impulses and retyping the message from saidimpulses.

8. The method which consists in typing a message, completely scanning bylight rays each letter character thereof before proceeding to the next,producing electrical impulses by said light rays, and producing lightflashes proportional to said impulses.

9. The method which consists in typing a message, completely scanning bylight rays each letter character thereof before proceeding to the next,producing electrical impulses from said light rays, producing lightflashes proportional to said impulses and making a record of saidflashes on a light sensitive medium;

10. The method which consists in typing a message, completely scanningby light rays each letter character thereof before proceeding to thenext, producing electrical impulses from said light rays,producing'light flashes proportional to said impulses, making a recordof said flashes on a light sensitive medium, and producing electricalimpulses proportional to said flashes.

11. The method which consists in typing a message, completely scanningby light rays each letter character thereof before proceeding to thenext, producing electrical impulses from said light rays, producinglight flashes proportional to said impulses, making a record of saidflashes on a light sensitive me dium, producing electrical impulsesproportional to said flashes, and producing at another point electricalimpulses proportional to the second mentioned impulse.

12. The method which consists in typing a message, completely scanningby light rays each letter character thereof before proceedingto thenext, producing electrical impulses from said light rays, producinglight flashes proportional to said impulses, making a record of saidflashes on a light sensitive. medium, producing electrical impulsesproportional to said flashes, producing at another point electricalimpulses proportional to the" second mentioned impulse, and producinglight flashes proportional to said last mentioned impulses.

13. The method which consists in typing a message, completely scanningby light rays each letter character thereof before roceeding to thenext, producing electrical impulses from said light rays, producinglight flashes proportional to said impulses, making a record of saidflashes on a light sensitive medium, producing electrical impulsesproportional to said flashes, producing at another point electricalimpulses proportional to the second mentioned impulse, producing lightflashes proportional to said last mentioned impulses, and then recordingsaid flashes in a light sensitive medium.

14. The method which consists in typing a message, completely scanningby light rays each letter character thereof before proceeding to thenext, producing electrical impulses from said light rays, producinglight flashes proportional to said impulses, making 2. record of saidflashes on a light sensitive medium, producing electrical impulsesproportional to said flashes, producing at another point electricalimpulses proportional to the second'mentioned impulse, producing lightflashes proportional to said last mentioned impulses, then recordingsaid flashes in a light sensitive medium, and retyping said message bymeans of said last mentioned flashes. I

15. The method of communication which consists in typing a message,interrupting light by the typed character, passing the interrupted lightonto a photoelectric element to produce a varying current, producing avariable light by said current and making a record from said variablelight.

16. The method of communication which consists in modulating anelectrical current in accordance with a plurality of messages to betransmitted, producing light from said current, making a photographicrecord from said light, modulating an electrical current from saidrecord and transmitting said current.

17 The method of communication which consists in modulating anelectrical current in accordance with a plurality of messages to betransmitted, producing light from said current, making a photographicrecord-from said light, modulating an electrical current from saidrecord, transmitting said current, and making another photographicrecord at the receiving end therefrom.

18. The method of communication which consists in modulating anelectrical current in accordance with a plurality of messages to betransmitted, producing light from said current, making a photographicrecord from said, light, modulating an electrical current from saidrecord, transmitting said current, making another photographic record atthe receiving end therefrom and making the llu original form of saidmessages from said last mentioned record.

19. The step in the method of communicating messages which consists intransmit- 5, ting light by each entire character in said message to forma single pulse of current by each character and making a photographicrecord of said pulses.

20. The step in the method of communi- 10 cation which consists intyping a message, passing each typed character in front of a lightsource, forming a single pulse of current from the light that istransmitted by the whole of each character and making a 15 record of thesaid pulses.

21. The method of communicating messages which consists in transmittinglight by each entire character in said message to form a single pulse ofcurrent for each of 20 said characters, transmitting all said pulses Iand converting the pulses at the receiving end into the originalcharacters of the message.

22. The method of communication which 85 consists in typing a messa e,passing each typed character in front 0 a light source, forming a singlepulse of current from the light that is transmitted by the whole of eachcharacter, making a record of the said 8 pulses, converting said recordinto current pulses, transmitting said pulses to a receiving stationmaking at the receiving station a record 0 the current pulses andforming each on final characters from the correspond- 85 ing pulse.

11 testimony whereof, I have signed my name to this specification this27 day of September, 1929.

, BYRON E. ELDRED.

